Sheath for knives



SHEATH FOR KNIVES Filed NOV. 21, 1966 INVENTOR DONALD H. DeVAUGHN United States Patent 3,381,807 SHEATH FOR KNIVES Donald H. De Vaughn, 106 Redgewood Drive, San Rafael, Calif. Filed Nov. 21, 1966, Ser. No. 595,851 3 Claims. (Cl. 206-16) ABSTRACT OF THE DISCLOSURE A sheath for knives comprising side walls of a resiliently yieldable material having inwardly arched middle areas, and provided along the summit lines and the base lines of said arched areas inwardly projecting, longitudinally extending ribs.

The present invention relates to the problem of sheathing heavy and sharp edged knife blades, such as the microtome knives employed in hospitals and medical laboratories for slicing organic tissue for the purpose of microscopic examination. Knives of the weight and keenness of blade of microtomes are liable to cut into the wall of a sheath and suffer damage to their cutting edges when subjected to shocks, vibrations or any rapid motion. This is particularly true after periods of practical use when the initial width of the blade has been diminished by repeated honing. Under such conditions the blade will rattle in a sheath that may initially have provided a perfect fit, thus greatly increasing the likelihood that the edge of the blade may come to harm.

It is an object of the invention to provide a slip sheath for knives of the type referred to, wherein the blade of the knife is dependably kept out of contact with the wall of the sheath. I

Another object of the invention is to provide a sheath of the type described, wherein the blade will not rattle even after its width has been reduced by repeated honing.

Still another object of the invention is to provide a sheath of the type referred to, into which the blade cannot be placed in wrong position, i.e. which is effective to protect the blade whether the knife is placed into the sheath in upright or upside down position.

Yet another object of the invention is to provide a sheath of the type referred to, that is of simple and inexpensive construction.

Another problem encountered with microtome blades is that the corners of their edges are a potential source of injury to attending personnel when used in slicing apparatus.

It is yet another object of the invention to provide guard means which shield the corners of the blade against accidental contact yet leave the main portion of the blade free and ready for use.

These and other objects of the invention will be apparent from the following description of the accompanying drawing which illustrates certain preferred embodiments thereof and wherein FIGURE 1 is a perspective of a two-part slip sheath embodying my invention, illustrating it in a position wherein its two parts are partially slipped over a microtome knife;

FIGURES 2A and 2B are vertical cross sections of the sheath shown in FIGURE 1 illustrating different functional positions thereof;

FIGURE 3 is a vertical cross section, similar to FIG- URE 2B illustrating a modified embodiment of the invention;

FIGURE 4 is a front elevation of a microtome knife provided with corner guards embodying the principles of my invention.

The knife sheath of my invention consists of two sym- 3,381,807 Patented May 7, 1968 'ice metrically identical parts 10' and 10" that are slipped over the knife blade 12 from opposite ends thereof as illustrated in FIGURE 1. The sheath parts 10 and 10" are made from a resiliently yieldable material, such as the plastic polypropylene. Each part is of rounded rectangular contour and has a wall 14 at one end and is open at the opposite end. The side walls 15:: and 15b of each part have inwardly arched areas 16a and 16b, respectively, and provided along the summit line of each of said inwardly arched wall areas is a longitudinally extending inwardly projecting ridge or rib 18a and 18b, as the case may be. These ribs terminate in smoothly rounded surfaces and are of such depth that the space between them is slightly less than the width of the knife blade 12 for which the sheath is designed, at the level of said ribs (FIGURES 2A and 2B). A short distance above the ribs 18a and 18b respectively, such as for instance along the base lines of the arched areas 16a and 16b, each of the side walls 16a and 16b is provided with additional inwardly directed ribs 20a and 20b respectively, which may be of the same depth as the ribs 18a and 18b but project to a lesser degree into the interior of the sheath than the centrally located ribs 18a and 18b due to their location at the base lines rather than the summit lines of the arched wall areas 16a and 16b. Again the space between each set of opposed ribs 20a and 20b is preferably slightly less than the width of the diverging end portion of the knife blade at the level at which said diverging end portion of the blade would be contacted by said ribs depending upon the position in which the knife is received in the sheath.

The top wall 22 and the bottom wall 24 of the sheath parts 10' and 10" are arranged to form inwardly directed longitudinally extending pedestals 26 and 28, respectively, that present flat surfaces upon which the blunt edge 30 of the knife blade 12 may rest. Due to the presence of these two pedestals and due to the presence of the ribs of lesser depth at either side of the centrally located ribs, the sheath parts may be applied to the knife blade, irrespective of Whether the blade is received in the sheath with its blunt edge 30 down and its sharp edge 32 up, or its blunt edge up and its sharp edge down. In both instances the ribs 18a and 18b along the summit line of the arched areas 16a and 16b and either the higher or the lower ribs 20a and 20b will be engaged and urged slightly backwards by the sides of the blade. This causes the arched areas to flatten out to a limited degree and may even cause the side walls to yield as a whole to a very small extent (FIGURE 2B). The strain of said side walls, and especially of their arched areas, to regain their initial shape, enables the center ribs 18a and 18b and the engaged set of the ribs 20a and 20b to hold the blade securely in a position wherein it cannot shift within the sheath and its sharp edge cannot come against one of its end walls. Thus the edge of the knife cannot come to harm and the sheath cannot be damaged. This holds true even if the depth of the blade is diminished as it will inevitably be in time, due to the necessity of resharpening it.

FIGURE 3 illustrates a modified embodiment of the invention wherein the center areas of the side walls 40a and 40b of each sheath part are shaped to form inwardly directed convexities 42a and 42b that engage and bear against the sides of the blade 12 at an intermediate level, and the lower areas 44a and 44b of said side Walls and the bottom wall 45 form a smoothly rounded receptacle for the blunt edge of the knife blade while the upper areas 46a and 46b of the side walls converge to form a wedge-shaped receptacle 48 within which the sharp edge of the blade may rest without danger of coming into contact with the sheath. In practical use the embodiment of the invention shown in FIGURE 3 differs from the embodiment illustrated in FIGURES 1, 2A and 2B in that it can properly be applied to the knife blade only in the position shown.

As pointed out hereinbefore, the corners of the sharp edges of microtomes are a frequent source of injury to personnel handling these knives in unsheathed condition, and particularly to the technicians operating the slicing apparatus upon which the microtome is mounted. This is especially serious because of the ever present danger that any injuries incurred by the technicians may be infected from the potentially diseased tissue which is being sliced by the microtorne for microscopic examination. In accordance with the invention this danger may be eliminated by corner guards 50 and 50" (FIGURE 4) which are constructed in the same manner as the sheath parts described hereinbefore and illustrated in FIGURES 1, 2A, 2B and 3 except that they are of much shorter length in a direction longitudinally of the knife blade. Due to the manner in which the ribs 20a and 20b, and especially the ribs 18a and 18b along the summit line of the arched side wall areas 16a and 16b are pressed against the knife blade, as the deformed side walls of resiliently yieldable material, and especially their arched areas 16a and 16b, strain to regain their initial shape, the corner guards 50' and 50" remain dependably in position once applied to the ends of a microtome blade even though the blade may be subjected to vibrations and shocks during operation of the slicing apparatus. Thus, the technicians manipulating the slicing apparatus are effectively protected from injury and infection.

While I have explained my invention with the aid of certain exemplary embodiments thereof, it will be understood that the invention is not limited to the specific constructional details shown and described by way of example, which, may be departed from without departing from the scope and spirit of the invention.

I claim:

1. A knife sheath comprising side walls of a resiliently flexible material having inwardly arched middle areas, and inwardly projecting, longitudinally extending ribs provided along the summit lines of said arched areas.

2. A sheath according to claim 1 including longitudinal ribs provided along the base lines of said arched areas.

3. A sheath according to claim 1 including top and bottom walls each forming an inwardly directed, longitudinally extending pedestal presenting a fiat surface to the space defined between the walls.

References Cited UNITED STATES PATENTS 831,770 9/ 1906 Bragg 224-2 1,919,811 7/1933 Stonebraker 206-165 3,283,894 11/1966 Hafner et al 206-165 FOREIGN PATENTS 203,493 10/ 1908 Germany.

376,938 9/ 1939 Italy.

GERALD M. FORLENZA, Primary Examiner.

R. L. BALLANTYNE, Assistant Examiner. 

